1. Ethel Percy Andrus Gerontology Center of the Davis School of Gerontology, University of Southern California, 3715 McClintock Avenue, Los Angeles, CA 90089-0191, U.S.A.
2. Division of Molecular and Computational Biology, Department of Biological Sciences of the College of Letters, Arts and Sciences, University of Southern California, 3715 McClintock Avenue, Los Angeles, CA 90089-0191, U.S.A.
3. Institute of Nutrition, Friedrich Schiller University, Jena 07743, Germany